I think Cavani has been equal parts shit and unlucky with his finishing when it comes to Champions League. I also think PSG mostly have themselves to blame for it, for playing him on the wing for so long. They made him blunt.
If someone like Wenger had gotten hold of Cavani three or four years ago and played him up front he could have turned him into a player without weaknesses; one of the best strikers of the last 20 years.